Wirtzfeld L A, Graham K C, Groom A C, Macdonald I C, Chambers A F, Fenster A, Lacefield J C
Biomedical Engineering Graduate Program, University of Western Ontario, London, Ontario, N6A 5B9, Canada.
Phys Med Biol. 2006 May 21;51(10):2367-81. doi: 10.1088/0031-9155/51/10/002. Epub 2006 Apr 26.
The identification and quantification of tumour volume measurement variability is imperative for proper study design of longitudinal non-invasive imaging of pre-clinical mouse models of cancer. Measurement variability will dictate the minimum detectable volume change, which in turn influences the scheduling of imaging sessions and the interpretation of observed changes in tumour volume. In this paper, variability is quantified for tumour volume measurements from 3D high-frequency ultrasound images of murine liver metastases. Experimental B16F1 liver metastases were analysed in different size ranges including less than 1 mm3, 1-4 mm3, 4-8 mm3 and 8-70 mm3. The intra- and inter-observer repeatability was high over a large range of tumour volumes, but the coefficients of variation (COV) varied over the volume ranges. The minimum and maximum intra-observer COV were 4% and 14% for the 1-4 mm3 and <1 mm3 tumours, respectively. For tumour volumes measured by segmenting parallel planes, the maximum inter-slice distance that maintained acceptable measurement variability increased from 100 to 600 microm as tumour volume increased. Comparison of free breathing versus ventilated animals demonstrated that respiratory motion did not significantly change the measured volume. These results enable design of more efficient imaging studies by using the measured variability to estimate the time required to observe a significant change in tumour volume.
对于癌症临床前小鼠模型的纵向非侵入性成像的正确研究设计而言，识别和量化肿瘤体积测量的变异性至关重要。测量变异性将决定最小可检测体积变化，这反过来又会影响成像 sessions 的安排以及对观察到的肿瘤体积变化的解释。在本文中，对来自小鼠肝转移瘤的 3D 高频超声图像的肿瘤体积测量变异性进行了量化。对实验性 B16F1 肝转移瘤在不同大小范围内进行了分析，包括小于 1 mm3、1 - 4 mm3、4 - 8 mm3 和 8 - 70 mm3。在很大范围的肿瘤体积内，观察者内和观察者间的重复性都很高，但变异系数（COV）在不同体积范围内有所变化。对于 1 - 4 mm3 和 <1 mm3 的肿瘤，观察者内 COV 的最小值和最大值分别为 4%和 14%。对于通过分割平行平面测量的肿瘤体积，随着肿瘤体积增加，保持可接受测量变异性的最大切片间距离从 100 微米增加到 600 微米。自由呼吸与通气动物的比较表明，呼吸运动并未显著改变测量体积。这些结果能够通过使用测量的变异性来估计观察到肿瘤体积显著变化所需的时间，从而设计出更高效的成像研究。
